136kHz Direct Conversion Receiver by IK2PII
I describe a simple direct conversion receiver, thinked for QRSS and DFCW communications, as companion of ARGO or SPECTRAN programs. The receiver is useful also as portable receiver, fast turn-on receiver for a quick look an the band or as very low cost (and performances) spectrum analyzer.
http://www.qsl.net/ik2pii/lf/dcrx136.htm

136kHz Converter door PA3GZC
Omdat mijn HF-transceiver (30kHz. - 30MHz.) op de nieuwe 136 kHz. banderg ongevoelig is, heb ik een converter gebouwd dat met een locale X-tal oscillator op 10.000 MHz. omhoog mengt naar 10.136 MHz.
http://www.a63.org/cqfrwden/jrg13/feb-99/136kc.htm

136 kHz one knob QRSS receiver by IK2PII
I don't like knobs, pushbuttons, blinking leds and so on whistles and bells on the receivers front panels. For digital modes the ideal receiver must be very simple, front end selectivity, manually adjustable gain, IF filter. All the goodies you can find on the HF receivers can be done by software.
http://www.qsl.net/ik2pii/lf/okqrssrx.htm

137 kHz QSD Receiver de F1AFJ
QSD c’est quoi ? : Quadrature Sample Detector ( voir le schéma pour le principe de fonctionement ) Ce détecteur a été inventé il y a seulement quelques années par un radioamateur américain, Dave Tayloe N7VE.
http://jpmere.online.fr/L_F/Les%20LF.htm

Active Loop Converter for the LF Band by VK5BR
In the converter which is described, a loop antenna is used as the only tuned inductive element with positive feedback applied to increase its effective Q and sharpen up its tuning. This of course is the old trick called reaction or regeneration used in the early days of TRF receivers to improve selectivity.
http://users.tpg.com.au/users/ldbutler/ActiveLoopConverter.htm

A very simple receiver for 136kHz by SQ5BPF
This project is a very simple receiver for the 136kHz band, with an 12kHz IF. The IF can be fed into a sound card and further processed in software (for example in Spectrum Lab) to get a waterfall spectrum plot, receive CW by ear etc.
https://klubnl.pl/wpr/en/index.php/artykuly/bardzo-prosty-odbiornik-136khz/

A LowFER Receiver Using a "Software" IF by KØLR
This article describes a "software" receiver that uses a simple, low cost hardware downconverter in conjunction with sound-card software such as DL4YHF's "Spectrum Lab" or I2PHD's "SDRadio", which act as a tunable DSP-IF system.
http://www.qsl.net/k0lr/SW-RX/sw-rx.htm

A very simple VLF Pocket receiver by DJ1WF
The following receiver concept may give an idea how to build a tiny and sufficiently performant RX without using expensive filters.
http://www.vlf.it/fritz/pocketrx.html

A VLF-LF receiver - 10kHz to 500 kHz with resistance tuning. by VK5BR
The receiver design is a little different from the usual form. It has no variable capacitors or inductors except for one preset trimmer in a trap circuit. Tuning is carried out by a potentiometer, the resistance of which sets the frequency of the heterodyne oscillator.
http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/ar/1989/12/page10/index.html

Ricevitore VLF Valvolare by IWØBZD
Il circuito di seguito descritto è stato appositamente progettato per tale scopo. La sua caratteristica innovativa è proprio quella di poter funzionare con una unica tensione continua di 12 V e poter essere all’occorrenza alimentato con una piccola batteria NiCa o Pb di quelle utilizzate in genere per i flash professionali o antifurti. Il circuito, in queste condizioni, è in grado fornire, dato il suo esiguo assorbimento di corrente, molte ore di funzionamento.
http://www.qsl.net/iw0bzd/VLF_TUBE_RX.htm

Using a PC with soundcard as a VLF receiver by DL4YLP
This article describes how to use your PC as a receiver for narrow-band signals in the VLF radio spectrum.
http://www.qsl.net/dl4yhf/speclab/vlf_rcvr.htm

VLF/LF to 28.5 MHz Receiving Converter by DF3LP
This converter is one of my early projects. It is built using "ugly style" in a small metallic case usingBNC for in- and output connection including some internal shielding of the crystal oscillator.
http://www.qsl.net/df3lp/projects/lfconv/index.html

VLF nach KW-Konverter durch DG7XO
Dieser Converter stammt von der Homepage http://www.radiosky.com ab.Ich habe dazu ein Layout für ein OM aus unserem OV gemacht, dass ich auch hier zur Verfügung stellen möchte.
http://www.dg7xo.de/selbstbau/vlf2kw.html